U.S. patent number 9,344,779 [Application Number 13/602,722] was granted by the patent office on 2016-05-17 for method and apparatus for space-division multiplexing systems.
This patent grant is currently assigned to Alcatel Lucent. The grantee listed for this patent is Alan H. Gnauck, Xiang Liu, Chandrasekhar Sethumadhavan, Peter J. Winzer. Invention is credited to Alan H. Gnauck, Xiang Liu, Chandrasekhar Sethumadhavan, Peter J. Winzer.
United States Patent |
9,344,779 |
Sethumadhavan , et
al. |
May 17, 2016 |
Method and apparatus for space-division multiplexing systems
Abstract
A space division multiplexed (SDM) transmission system that
includes at least two segments of transmission media in which a
spatial assignment of the two segments is different is provided.
For example, the SDM transmission may include a first segment of
transmission media having a first spatial assignment and a second
segment of transmission media having a second spatial assignment,
wherein the first spatial assignment differs from the second
spatial assignment. An example method obtains an optical signal on
a first segment of transmission media having a first spatial
assignment and forwards the optical signal on a second segment of
transmission media with a different spatial assignment. The
transmission media may be a multi-core fiber (MCF), a multi-mode
fiber (MMF), a few-mode fiber (FMF), or a ribbon cable comprising
nominally uncoupled single-mode fiber (SMF).
Inventors: |
Sethumadhavan; Chandrasekhar
(Matawan, NJ), Liu; Xiang (Marlboro, NJ), Winzer; Peter
J. (Aberdeen, NJ), Gnauck; Alan H. (Middletown, NJ) |
Applicant: |
Name |
City |
State |
Country |
Type |
Sethumadhavan; Chandrasekhar
Liu; Xiang
Winzer; Peter J.
Gnauck; Alan H. |
Matawan
Marlboro
Aberdeen
Middletown |
NJ
NJ
NJ
NJ |
US
US
US
US |
|
|
Assignee: |
Alcatel Lucent
(Boulogne-Billancourt, FR)
|
Family
ID: |
46846025 |
Appl.
No.: |
13/602,722 |
Filed: |
September 4, 2012 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130236175 A1 |
Sep 12, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61530929 |
Sep 2, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B
6/26 (20130101); H04J 14/00 (20130101); H04J
14/021 (20130101); H04J 14/02 (20130101); G02B
6/29383 (20130101); H04Q 11/0003 (20130101); H04J
14/04 (20130101); H04J 14/0212 (20130101); G02B
6/02042 (20130101) |
Current International
Class: |
G02B
6/036 (20060101); H04J 14/04 (20060101); H04J
14/00 (20060101); G02B 6/26 (20060101); G02B
6/293 (20060101); H04Q 11/00 (20060101); H04J
14/02 (20060101); G02B 6/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1396742 |
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Mar 2004 |
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EP |
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1396742 |
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Mar 2004 |
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EP |
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10197739 |
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Jul 1998 |
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JP |
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PCT/US2012/053663 |
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Oct 2012 |
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WO |
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Other References
Sethumadhavan Chandrasekhar et al "WDM/SDM transmission of
10.times.128-Gb/s PDM-QPSK over 2688-km 7-core fiber with a
per-fiber net aggregate spectral-efficiency distance product of
40,320 km.b/s/Hz" --Jan. 16, 2012/ vol. 20, No. 2--Optics Express
706--6 pages. cited by applicant .
Sakaghuchi et al "109-Tb/s (7.times.97.times.712-Gb/s SDM/WDM/PDM)
QPSK transmission through 16.8-km homogeneous multi-core fiber"
OSA/OFC/NFOEC 2011--3 pages. cited by applicant .
Zhu et al "Space-, Wavelength-, Polarization--Division Multiplexed
Transmission of 56-Tb/s over a 76.8-km Seven-Core Fiber"
OSA/OFC/NFOEC 2011--3 pages. cited by applicant .
Zhu et al. Seven-core Multicore Fiber Transmissions for passive
Optical Network--May 24, 2010, vol. 18, No. 11--Optics Express--6
pages. cited by applicant .
Robert Tkach "Scaling Optical Communications for the Next Decade
and Beyond" Bell Labs Technical Journal 14 (4), 3-10 (2010) 7
Pages. cited by applicant .
Zhu et al --"112-TB/s Space-division multiplexed DWDM transmission
with 14-b/s/Hz Aggregate Spectral Efficiency over a 76.8-km
seven-core fiber" Aug. 15, 2011--vol. 19, No. 17--Optics Expres--7
pages. cited by applicant .
Savory " Digital Coherent Optical Receivers: Algorithms and
Subsystems" IEEE Journal of Selected Topics in Quantum Electronics,
vol. 16, No. 5, Sep./Oct. 2010--16 pages. cited by applicant .
Vitesse "Making Next-Generation Networks a Reality" Enchanced FEC
for 40G/100G--OFC-NFOEC, Mar. 2010--11 Pages. cited by applicant
.
Al Amin a et al: "Spatial Mode Division Multiplexing for Overcoming
Capacity Barrier of Optical Fibers". Optoelectronics and
Communications Conference (OECC), 2011 16th, IEEE, Jul. 4,
2011--pp. 415-416. cited by applicant.
|
Primary Examiner: Peace; Rhonda
Attorney, Agent or Firm: Ralston; Andrew R.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Patent
Application No. 61/530,929, filed on Sep. 2, 2011, entitled "Method
and Apparatus for Space-Division Multiplexing Systems," which is
incorporated herein by reference in its entirety.
Claims
What is claimed is:
1. A space division multiplexed (SDM) transmission system
comprising: first and second segments of multicore optical fiber;
an optical add-drop multiplexer (OADM) configurable to add and drop
wavelength channels of a wavelength-division multiplexed optical
signal; a first singlecore-to-multicore connector configured to
connect individual cores of said first segment to inputs of said
OADM; and a second singlecore-to-multicore connector configured to
connect outputs of said OADM to individual cores of said second
segment, wherein a first fiber core of said first segment is
connected to a fiber core of said second segment other than a fiber
core corresponding to said first fiber core of said first
segment.
2. The SDM transmission system of claim 1, wherein a spatial
assignment of said optical cores of said second multicore optical
fiber is altered from a spatial assignment of said optical cores of
said first multicore optical fiber in a cyclic fashion.
3. The SDM transmission system of claim 1, wherein a spatial
assignment of said optical cores of said second multicore optical
fiber varies from a spatial assignment of said optical cores of
said first multicore optical fiber according to a predetermined
pattern.
4. The SDM transmission system of claim 1, wherein said OADM
comprises a reconfigurable optical add drop multiplexer
(ROADM).
5. The SDM transmission system of claim 1, wherein the optical add
drop multiplexer contains an N-input N-output optical switch.
6. The SDM transmission system of claim 1, further comprising a
transmitter and a receiver, wherein the first segment and the
second segment comprise a link between the transmitter and the
receiver.
7. The SDM transmission system of claim 1, wherein said OADM is a
first OADM, and further comprising a second OADM and a third OADM,
wherein the first segment and the second segment comprise a link
between the second OADM and the third OADM.
8. The SDM transmission system of claim 1, further comprising a
first amplifier and a second amplifier, wherein the first segment
and the second segment comprise a link between the first amplifier
and the second amplifier.
9. A method comprising: obtaining an optical signal on a first
multicore optical fiber segment; forwarding the optical signal to a
second multicore optical fiber segment, wherein the optical signal
is forwarded via a first singlecore-to-multicore connector that
connects individual cores of said first segment to inputs of an
optical add-drop multiplexer (OADM) or an optical amplifier;
wherein the optical signal is forwarded via a second
singlecore-to-multicore connector that connects outputs of said
OADM or said optical amplifier to individual cores of said second
segment, and wherein spatial assignment of optical cores of said
first and second multicore optical fibers segments is altered such
that a first fiber core of said first segment is connected to a
single fiber core of said second segment other than a fiber core
corresponding to said first fiber core of said first segment.
10. The method of claim 9, wherein the obtaining and forwarding are
performed at multiple locations along a transmission link, and
wherein spatial assignment alteration is performed at multiple
locations along said transmission link.
11. The method of claim 9, wherein the spatial assignment of said
optical cores of said second multicore optical fiber segments is
altered from the spatial assignment of said optical cores of said
first multicore optical fiber segments in a cyclic fashion.
12. The method of claim 9, wherein the spatial assignment of said
optical cores of said second multicore optical fiber is altered
from the spatial assignment of said optical cores of said first
multicore optical fiber according to a predetermined pattern.
13. The method of claim 9, wherein said OADM comprises a
reconfigurable optical add drop multiplexer (ROADM).
14. The method of claim 9, wherein said OADM comprises an N-input
N-output optical switch.
15. A space division multiplexed (SDM) transmission system
comprising: a first and second of multicore optical fiber segments;
a plurality of optical amplifiers; a first singlecore-to-multicore
connector configured to connect individual cores of said first
segment to individual ones of said amplifiers; and a second
singlecore-to-multicore connector configured to connect outputs of
individual ones of said amplifiers to individual cores of said
second segment, wherein a first fiber core of said first segment is
connected to a single fiber core of said second segment other than
a fiber core corresponding to said first fiber core of said first
segment.
16. The SDM transmission system of claim 15, wherein a spatial
assignment of said optical cores of said second multicore optical
fiber segment is altered from a spatial assignment of said optical
cores of said first multicore optical fiber segment in a cyclic
fashion.
17. The SDM transmission system of claim 15, wherein a spatial
assignment of said optical cores of said second multicore optical
fiber segment varies from a spatial assignment of said optical
cores of said first multicore optical fiber segment according to a
predetermined pattern.
18. The SDM transmission system of claim 15, further comprising a
transmitter and a receiver, wherein the first segment and the
second segment comprise a link between the transmitter and the
receiver.
19. The SDM transmission system of claim 15, further comprising a
second amplifier and a third amplifier, wherein the first segment
and the second segment comprise a link between the second amplifier
and the third amplifier.
20. A space division multiplexed (SDM) transmission system
comprising: a first multicore optical fiber having a first
plurality of optical cores; and a second multicore optical fiber
having a second plurality of optical cores, wherein a first fiber
core of said first plurality of optical cores is connected to a
single second fiber core of said second multicore optical fiber
other than a first fiber core of said second multicore optical
fiber that corresponds to said first fiber core of said first
multicore optical fiber.
21. The SDM transmission system of claim 20, wherein said first and
second fiber cores are connected via an optical add-drop
multiplexer (OADM).
22. The SDM transmission system of claim 20, wherein said first
plurality of optical cores are connected to said second plurality
of optical cores according to a cyclic core index shift.
23. The SDM transmission system of claim 20, wherein said first and
second fiber cores are connected via an optical amplifier.
Description
BACKGROUND
1. Field
The invention relates to optical communication equipment and, more
specifically but not exclusively, to transmission of optical
communication signals in space-division multiplexing (SDM) systems
using multi-core fiber (MCF), multi-mode fiber (MMF), few-mode
fiber (FMF), or ribbon cable made of nominally uncoupled
single-mode fiber (SMF) as the transmission media.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better
understanding of the invention(s) described herein. Accordingly,
the statements of this section are to be read in this light and are
not to be understood as admissions about what is in the prior art
or what is not in the prior art.
Performance variations among signals traveling through transmission
media impair the transmission performance of systems, including for
example the transmission performance of space-division multiplexing
(SDM) systems. Thus, one technical problem related to such
transmission systems is how to increase the transmission
performance of SDM systems using multi-core fiber (MCF), multi-mode
fiber (MMF), few-mode fiber (FMF), or ribbon cable made of
nominally uncoupled single-mode fiber (SMF) as the transmission
media. In particular, the performance variations among the signals
traveling through the multiple cores of a MCF, or multiple modes of
a MMF, or multiple fibers of a ribbon cable need to be minimized in
order to improve transmission performance.
One existing solution to address transmission performance of such
transmission systems is to increase the uniformity of the
transmission characteristics of the MCF, such as loss, dispersion,
and crosstalk, through better and improved fiber design and
manufacturing. However, this approach has limited performance
benefits and becomes increasingly expensive as the uniformity
requirement is increased. Further, for MMF, higher-order modes
generally have higher loss than the fundamental mode, and it is
difficult to make the losses of different modes equal.
SUMMARY
According to one embodiment of a MCF-based transmission system, the
optical signals traveling through each of the cores of a MCF span
are moved to another core in the next MCF span. This core-to-core
signal rotation may be continued at multiple locations along a MCF
transmission link. The locations where the core-to-core rotation is
applied can be (1) optical add/drop multiplexer (OADM) sites, (2)
optical amplifier sites, or (3) the combination of (1) and (2). By
doing the core-to-core rotation, the uniformity in loss,
dispersion, and signal arrival time can be much improved, thereby
increasing the overall system performance. As it is likely that one
or more cores or modes will have increased crosstalk relative to
the others, embodiments of the described technique can help reduce
the performance variation of spatially multiplexed signals by
distributing the crosstalk penalty among all of the spatially
multiplexed signals. In addition, the system degradation resulting
from some optical component defects, such as the loss ripple and
polarization-dependent loss (PDL) in OADMs and optical amplifiers,
can be reduced through the "averaging" effect of the core-to-core
rotation.
For MMF, different modes generally have different transmission
characteristics. For future-generation tightly-packed ribbon cable,
it is likely that different strands have different properties,
depending on where the individual strand is located within the
ribbon in the cable cross-section. Accordingly, the base idea of
core-to-core rotation described above can be straightforwardly
extended to MMF-based and fiber-ribbon-based transmission systems
by using mode-to-mode signal rotation and fiber-to-fiber rotation,
respectively, rather than the core-to-core rotation used in the MCF
case. Note that these three variants of rotation can be used
together in systems where MCF, MMF, and fiber ribbon are used in
combination.
BRIEF DESCRIPTION OF THE DRAWINGS
Example embodiments will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings. The Figures represent non-limiting, example
embodiments as described herein.
FIG. 1 shows a block diagram of a first embodiment of a space
division multiplexed (SDM) transmission system according to an
embodiment of the invention; and
FIG. 2 shows a block diagram of a second embodiment of a space
division multiplexed (SDM) transmission system according to an
embodiment of the invention.
DETAILED DESCRIPTION
FIG. 1 shows a block diagram of a first embodiment of a space
division multiplexed (SDM) transmission system according to an
embodiment of the invention. FIG. 1 illustrates a first embodiment
for core-to-core signal rotation in multi-core fiber (MCF)
transmission for a SDM transmission system 100. The optical signals
traveling through a MCF span are rearranged such that they travel
through the next MCF span on different cores of the MCF. As shown,
wavelength-division multiplexed (WDM) channels (C_1, C_2, . . .
C_M) may be provided to a singlecore-to-multicore-connector 110 for
connection to a first MCF span 120. (A fiber span may also be
called a fiber segment.) The channels are provided to the first MFC
span with a first spatial assignment. Naturally, the optical signal
or channels need not utilize wavelength-division multiplexing.
The MCF span 120 is traversed by the optical signals and provided
to a singlecore-to-multicore-connector 130. At this point, the
spatial assignment remains unchanged. The
singlecore-to-multicore-connector 130 provides the WDM channels to
Optical Add Drop Multiplexer (OADM) 140. Rearrangement of the
spatial assignment of the WDM channels can be easily performed in
an M-input M-output OADM by connecting the output ports of the OADM
to the input ports of the next singlecore-to-multi-core connector
150 with a cyclic core index shift, M being an integer. For
example, C_(1:M-1).fwdarw.C_(2:M); C_(M).fwdarw.C_1. That is; the
spatial assignment for the first to the M-1th channel of a first
fiber segment is switched to the next higher channel in the next
fiber segment, and spatial assignment of the M-th channel in the
first fiber segment is shifted to the first channel in the next
fiber channel. In another embodiment, the spatial assignment may
change according to a predetermined pattern. The M.times.M OADM can
be in the form of an M.times.M wavelength selective switch. The
OADM may also be a Reconfigurable OADM, nominally a ROADM.
FIG. 2 shows a block diagram of a second embodiment of a space
division multiplexed (SDM) transmission system according to an
embodiment of the invention. FIG. 2 illustrates a second embodiment
in which the core-to-core signal rotation is realized by suitably
arranging the connections between the outputs of optical amplifiers
and the input ports of the singlecore-to-multicore connector.
In the illustrated SDM transmission system 200, optical signals
traveling through a MCF span are rearranged such that they travel
through the next MCF span on different cores of the MCF. As shown,
wavelength-division multiplexed (WDM) channels (C_1, C_2, . . .
C_M) may be provided to a singlecore-to-multicore-connector 110 for
connection to a first MCF segment 220. The channels are provided to
the first MFC span with a first spatial assignment. Naturally, the
optical signal or channels need not utilize wavelength-division
multiplexing.
The MCF span 220 is traversed by the optical signals and provided
to a singlecore-to-multicore-connector 230. At this point, the
spatial assignment remains unchanged. The
singlecore-to-multicore-connector 230 provides the WDM channels to
a plurality of fiber amplifiers 240. In one embodiment, the fiber
amplifiers are erbium doped fiber amplifier (EDFA). Rearrangement
of the spatial assignment of the WDM channels can be easily
performed by suitably arranging the connections between the outputs
of optical amplifiers 240 and the input ports of the
singlecore-to-multicore connector connector 250. For example, the
spatial assignment between fiber segments can be altered so as to
be varied according to a cyclic core index shift or some other
predetermined pattern.
Note that a long MCF can usually be made out the same preform
design, so the core-to-core non-uniformity in loss and dispersion
could be similar from span to span. Rotating the signals through
different cores along a MCF fiber effectively reduces the negative
system impact of the core-to-care non-uniformity. Note also that
the core-to-core signal rotation may reduce the arrival time
difference among signals that originate from the same location and
terminate at the same destination. This may be beneficial for some
applications.
In other embodiments according to the principles of the invention,
the transmission media of the SDM transmission system may a
multi-mode fiber (MMF), a few-mode fiber (FMF), or a ribbon cable
made of nominally uncoupled single-mode fiber (SMF). For a
MMF-based transmission system, the single-core-to-multicore
connectors shown in FIGS. 1 and 2 will be replaced with
mode-splitters. Note also that the core-to-core rotation
(mode-to-mode) for MCF (FMF) can be implemented on a "sub-span"
basis, e.g., implemented when splicing short fiber segments
together to form a long MCF (FMF) fiber span.
One or more embodiments described herein may help increase the
overall performance of multi-core-fiber (MCF) and few-mode-fiber
(FMF) based transmission systems, which is of value in future
optical transmission systems that utilize MCF and FMF as the
transmission media to support high transmission capacity.
In one embodiment, a space division multiplexed (SDM) transmission
system comprises at least two segments of transmission media,
wherein a spatial assignment of the two segments is different. In
one embodiment, a space division multiplexed (SDM) transmission
system comprises a first segment of transmission media having a
first spatial assignment; and a second segment of transmission
media having a second spatial assignment; wherein the first spatial
assignment differs from the second spatial assignment.
In one embodiment, at least one respective segment of the
transmission media of the SDM transmission system is a multi-core
fiber (MCF), a multi-mode fiber (MMF), a few-mode fiber (FMF), or a
ribbon cable made of nominally uncoupled single-mode fiber
(SMF).
In one embodiment, the second spatial assignment is a rotated
version of the first spatial assignment. In one embodiment, the
second spatial assignment varies from the first spatial assignment
according to the predetermined pattern.
In one embodiment, fiber cores of the second segment are connected
to fiber cores of the first segment, a first fiber core of the
first segment being connected to other than a first fiber core of
the second segment. Thus, a first fiber core of the first segment
is connected to a fiber of the second segment other than a
corresponding first fiber core of the second segment. In one
embodiment, spatial modes of the second segment are connected to
spatial modes of the first segment, a first spatial mode of the
first segment being connected to other than a first spatial mode of
the second segment. Thus, a first spatial mode of the first segment
is connected to a spatial mode of the second segment other than a
corresponding first spatial mode of the second segment. In one
embodiment, fibers of the second segment are connected to fibers of
the first segment, a first fiber of the first segment being
connected to other than a first fiber of the second segment. Thus,
the optical signals traveling a first core of the first segment are
moved to a core of the second segment other than a corresponding
first core of the second segment.
In one embodiment, the spatial assignment is changed between the
first segment and the second segment by an optical add drop
multiplexer (OADM). The (OADM) may be a reconfigurable optical add
drop multiplexer (ROADM). In another embodiment, the optical add
drop multiplexer contains an N-input N-output optical switch.
In one embodiment, the spatial assignment is changed between the
first segment and the second segment by a fiber amplifier. In
another embodiment, the fiber amplifier is an N-input N-output an
Erbium doped fiber amplifier.
In one embodiment, the SDM transmission system includes a
transmitter and a receiver, and the first segment and the second
segment comprise a link between the transmitter and the receiver.
In another embodiment, the SDM transmission system includes a first
optical add drop multiplexer (OADM) and a second OADM, and the
first segment and the second segment comprise a link between the
first OADM and the second OADM. In yet another embodiment, the SDM
transmission system includes a first amplifier and a second
amplifier, wherein the first segment and the second segment
comprise a link between the first amplifier and the second
amplifier.
In one embodiment, a method comprises obtaining optical signal on a
first segment of transmission media having a first spatial
assignment, and forwarding the optical signal on a second segment
of transmission media having a different spatial assignment thereby
altering the spatial assignment of the optical signal.
In one embodiment, the transmission media is a multi-core fiber
(MCF), a multi-mode fiber (MMF), a few-mode fiber (FMF), or a
ribbon cable made of nominally uncoupled single-mode fiber (SMF).
In one embodiment, the transmission media is a multi-core fiber
(MCF) and the forwarding comprises moving the optical signals
traveling a first core of the first segment to a core other than
the first core of the second segment. In another embodiment, the
optical signals traveling a first core of the first segment are
moved to a core of the second segment other than a corresponding
first core of the second segment.
In one embodiment, the transmission media is a multi-mode fiber
(MMF) or a few-mode fiber (FMF) and the forwarding comprises moving
the optical signals traveling a first mode of the first segment to
a mode other than the first mode of the second segment. In another
embodiment, the optical signals traveling a first mode of the first
segment are moved to a mode of the second segment other than a
corresponding first mode of the second segment.
In one embodiment, the transmission media is a ribbon cable
comprising nominally uncoupled single-mode fiber (SMF) and the
forwarding comprises moving the optical signals traveling a first
single mode fiber of the first segment to a single mode fiber other
than the first single mode fiber of the second segment. In another
embodiment, the optical signals traveling a first single mode fiber
of the first segment are moved to a single mode fiber of the second
segment other than a corresponding first single mode fiber of the
second segment.
In one embodiment, the altering of the spatial assignment of the
optical signal occurs at an optical add/drop multiplexer (OADM)
site, reconfigurable add/drop multiplexer (ROADM) site, an optical
amplifier site, a point in a fiber span, or a combination
thereof.
In one embodiment, the obtaining and forwarding are performed at
multiple locations along a transmission link, whereby spatial
assignment alteration is performed at multiple locations along a
transmission link. The spatial assignment alternation may be
performed in a cyclic fashion or according to a predetermined
pattern.
In one embodiment, the first segment and the second segment
comprise a link between a transmitter and a receiver. In one
embodiment, the first segment and the second segment comprise a
link between two optical add drop multiplexers (OADMs). In one
embodiment, the first segment and the second segment comprise a
link between two amplifiers
Various provided embodiments offer a novel, different approach, a
system-level approach, to addressing the performance variations
among the signals traveling through the multiple cores of a MCF as
compared to the existing conventional approaches based on
generating better (improved) fiber design and manufacturing. As a
result, the embodiments provided herein may improve system
performance with essentially no additional cost.
While this invention has been described with reference to
illustrative embodiments, this description is not intended to be
construed in a limiting sense. Various modifications of the
described embodiments, as well as other embodiments of the
invention, which are apparent to persons skilled in the art to
which the invention pertains are deemed to lie within the principle
and scope of the invention as expressed in the following
claims.
Unless explicitly stated otherwise, each numerical value and range
should be interpreted as being approximate as if the word "about"
or "approximately" preceded the value of the value or range.
The use of figure numbers and/or figure reference labels in the
claims is intended to identify one or more possible embodiments of
the claimed subject matter in order to facilitate the
interpretation of the claims. Such use is not to be construed as
necessarily limiting the scope of those claims to the embodiments
shown in the corresponding figures.
Although the elements in the following method claims, if any, are
recited in a particular sequence with corresponding labeling,
unless the claim recitations otherwise imply a particular sequence
for implementing some or all of those elements, those elements are
not necessarily intended to be limited to being implemented in that
particular sequence.
Reference herein to "one embodiment" or "an embodiment" means that
a particular feature, structure, or characteristic described in
connection with the embodiment can be included in at least one
embodiment of the invention. The appearances of the phrase "in one
embodiment" in various places in the specification are not
necessarily all referring to the same embodiment, nor are separate
or alternative embodiments necessarily mutually exclusive of other
embodiments. The same applies to the term "implementation."
Also for purposes of this description, the terms "couple,"
"coupling," "coupled," "connect," "connecting," or "connected"
refer to any manner known in the art or later developed in which
energy is allowed to be transferred between two or more elements,
and the interposition of one or more additional elements is
contemplated, although not required. Conversely, the terms
"directly coupled," "directly connected," etc., imply the absence
of such additional elements.
The description and drawings merely illustrate the principles of
the invention. It will thus be appreciated that those of ordinary
skill in the art will be able to devise various arrangements that,
although not explicitly described or shown herein, embody the
principles of the invention and are included within its spirit and
scope. Furthermore, all examples recited herein are principally
intended expressly to be only for pedagogical purposes to aid the
reader in understanding the principles of the invention and the
concepts contributed by the inventor(s) to furthering the art, and
are to be construed as being without limitation to such
specifically recited examples and conditions. Moreover, all
statements herein reciting principles, aspects, and embodiments of
the invention, as well as specific examples thereof, are intended
to encompass equivalents thereof.
The functions of the various elements shown in the figures,
including any functional blocks labeled as "processors" and
"controllers," may be provided through the use of dedicated
hardware as well as hardware capable of executing software in
association with appropriate software. When provided by a
processor, the functions may be provided by a single dedicated
processor, by a single shared processor, or by a plurality of
individual processors, some of which may be shared. Moreover,
explicit use of the term "processor" or "controller" should not be
construed to refer exclusively to hardware capable of executing
software, and may implicitly include, without limitation, digital
signal processor (DSP) hardware, network processor, application
specific integrated circuit (ASIC), field programmable gate array
(FPGA), read only memory (ROM) for storing software, random access
memory (RAM), and non volatile storage. Other hardware,
conventional and/or custom, may also be included.
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